Are you talking about yandere simulator? Cause if you are, just kill a bunch of people in front of him, or go all up in his face with blood on your clothes.
Make him a boxed lunch. In the morning grab a piece of toast and run with it in your mouth while thinking "I hope senpai will accept it.. ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄ "
Fucking obliterate him and then put a muffin on his grave. Works every time for me
Poison your rivals food, brainwash them, get them electrocuted or expelled. Then come up to senpai at the last day of school and confess to him.
ask annoying questions
Tie them up and leave them on your bed
Cut of his/her arm.
what are some good ways to make Senpai notice me? ^-^